20 interview questions on Javascript - Security by design for developers (2026)

Easy

0 vote29 runs0 comment

Why is it recommended to use Web Workers to process sensitive or complex data?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote26 runs

1 comment

Identify the error in this code aiming to retrieve the value of the private field.

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WeLoveDevsat Sep 15, 2026

Hard

0 vote23 runs0 comment

Which approach guarantees the encapsulation of private data in a class without exposing the properties on the instance?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote16 runs0 comment

Why is it preferable to use JSON.parse() rather than eval() to transform a string into an object?

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WeLoveDevsat Sep 15, 2026

Hard

0 vote16 runs0 comment

What is the main risk associated with using this Map object?

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WeLoveDevsat Sep 15, 2026

Hard

0 vote15 runs0 comment

What is the fundamental difference between Map and WeakMap regarding reference management?

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WeLoveDevsat Sep 15, 2026

Easy

0 vote14 runs0 comment

What is the most concise and robust pattern to access a potentially missing nested property and provide a default value?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote13 runs0 comment

What is the behavior of this code when accessing proxy.name?

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WeLoveDevsat Sep 15, 2026

Easy

0 vote13 runs0 comment

What is the output of this code?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

Which expression completes the code to ensure the absence of a prototype?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

What is displayed in the console after executing this code?

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WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

What is the fundamental difference between Object.freeze() and Object.seal() in JavaScript?

Web developer

WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

What is the architectural advantage of using WeakMap rather than Map to associate private data with DOM objects?

Web developer

WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

What is the structural difference between encapsulation via a closure and via an ES module?

Web developer

WeLoveDevsat Sep 15, 2026

Hard

0 vote12 runs0 comment

What is the correct syntax to invoke the sanitize function as a tagged template?

Web developer

WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

What is the recommended method for inserting text content from a user into the DOM to prevent XSS flaws?

Web developer

WeLoveDevsat Sep 15, 2026

Easy

0 vote12 runs0 comment

Why ban the use of eval() in a secure application architecture?

Web developer

WeLoveDevsat Sep 15, 2026

Medium

0 vote12 runs0 comment

Identify the logical error preventing this asynchronous function from working properly.

Web developer

WeLoveDevsat Sep 15, 2026

Hard

0 vote11 runs0 comment

What is the main advantage of using structuredClone() compared to the JSON.parse(JSON.stringify(obj)) method?

Web developer

WeLoveDevsat Sep 15, 2026

Medium

0 vote11 runs0 comment

Why do browsers mandate the HTTPS protocol for registering Service Workers?

Web developer

WeLoveDevsat Sep 15, 2026

20 interview questions on Javascript - Security by designfor developers (2026)

Test your technical skills before an interview of Javascript - Security by design with 20 corrected questions. Beginner, Intermediate or Expert level.

Why is it recommended to use Web Workers to process sensitive or complex data?

Identify the error in this code aiming to retrieve the value of the private field.

Which approach guarantees the encapsulation of private data in a class without exposing the properties on the instance?

Why is it preferable to use JSON.parse() rather than eval() to transform a string into an object?

What is the main risk associated with using this Map object?

What is the fundamental difference between Map and WeakMap regarding reference management?

What is the most concise and robust pattern to access a potentially missing nested property and provide a default value?

What is the behavior of this code when accessing proxy.name?

What is the output of this code?

Which expression completes the code to ensure the absence of a prototype?

What is displayed in the console after executing this code?

What is the fundamental difference between Object.freeze() and Object.seal() in JavaScript?

What is the architectural advantage of using WeakMap rather than Map to associate private data with DOM objects?

What is the structural difference between encapsulation via a closure and via an ES module?

What is the correct syntax to invoke the sanitize function as a tagged template?

What is the recommended method for inserting text content from a user into the DOM to prevent XSS flaws?

Why ban the use of eval() in a secure application architecture?

Identify the logical error preventing this asynchronous function from working properly.

What is the main advantage of using structuredClone() compared to the JSON.parse(JSON.stringify(obj)) method?

Why do browsers mandate the HTTPS protocol for registering Service Workers?